Apparatus for making gas



May 2, 1933. w. G. LAlRD 1,906,470

APPARATUS FOR MAKING GAS Filed Jan. 30, 1929 4 Sheets-Sheet 1 WILBUR G. LAlRD-gwvc/wbo z May 2, 1933. w. G. LAIRD APPARATUS FOR MAKING GAS Filed- Jan. 30, 1929 4 Sheets-Sheet 2 ill WI LBUR G. Lman anpgwtoi W. G. LAIRD APPARATUS FOR MAKING GAS Filed Jan. 50, 1929 4 Sheets-Sheet 3 V90 64$ N k w 74 ag @670 if 7 9O 70 4 69 G 0 72 \a s (1% Ema 6 O w B e O c fl O 0O 3 60 85 60 6/ i 1" +fins/1M 5 A WPLBUR LmRD- wuewfo c May 2, 1933. w. G. LAIRD 1,906,470

APPARATUS FOR MAKING GAS Filed Jan. 50, 1929 4 Sheets-Sheet 4) 00 JL 1g WILBUR G. LRIRD aM UMO'D Patented May 2, 1933 UNITED STATES PATEN'B. OFFICE;

WILBUR G. LAIRD, OF NEW YORK, N. Y., ASSIGNOR T HEAT TREATING COMPANY, OF (I NEW YORK, N. Y., A CORPORATION OF DELAWARE APPARATUS FOR MAKING GAS Application filed January so, 1929. Serial No. 336,042.

This invention relates to apparatus for making gas and particularly to apparatus by which a cold, clean gas may be made through the primary or partial combustion of coal or other fuel containing volatile hydrocarbons.

This invention is a continuation in part of that describe-d in my co-pending application Serial No. 619,375, filed Feb. 16, 1923.

- If a fuel containing volatile hydrocarbons be employed in the common type of gas producer, in which the gas is formed by the primary combustion of the coal with air or air and steam, the volatile constituents of the coal are broken up at a comparaively high temperature, forming finely divided carbon or lamp black and heavy pitch. These proclucts are carried by the gas in the vapor state or as a suspension and, when the gas is permitted to cool, the pitch deposits, carrying with it carbon and cementing the carbon into a dense mass. This separation of pitch and lamp black is very troublesome as the conduits and passageways for the'gas become covered with it and can be cleared from it only with great difficulty, particularly if the pitch is subjected to contact with the hot gas and a long continued baking is thereby permitted to take place. Producer gas made in this manner must, accordingly, be maintained and used while sufiiciently hot to prevent the pitch from condensing out and the field'of usefulness of the gas is thereby restricted. To avoid or lessen the difficulties caused by the formation and deposition of pitch, coke may be used but, as coke is usually an expensive fuel and cooling the gas would lower the heat efficiency of the process, the advantages obtained by the use of coke are off- 6 set by other factors.

One object of the invention is to provide a simple, unitary apparatus by which a cold, clean, fuel gas of the producer type may be obtained from coal and similar fuels containing volatile constituents.

'A furtherobject of the invention is to provide apparatus for producing a fuel gas by the incomplete combustion of carbonaceous fuel in which the heat set free in said cornbustion is efliciently and effectively utilized in the gas making operations.

Further objects and features of the invention are the'utilization of fuels of various grades, some of which might not be otherwise utilizable for gas 'making, the carbonization of such fuels under uniform and accurately controlled conditions with heat from the hot producer gas and in a manner to remove andrecover a maximum ofvolatile products, the production of coke, the filtering of (e the producer gas and removal of pitch and other troublesome .constituents within the gas apparatus, and the recoveryand utilization of the sensible heat of the products within the gas apparatus to maintain the most effective temperature conditions for the eflicient pro- 6 duction of gas and utilization of fuel. With these other objects inview, the invention comprises the apparatus described and set forth in the following specification and claims.

The various features of the invention are illustrated in the accompanying drawings in which:

Fig. 1 is 'a sectional, diagrammatic, elevation of apparatus for making gas, embodying a preferred form of the invention, structural details being omitted for the sake of clearness, and,

Fig. 2 is a sectional view of the apparatus illustrated in Fig. 1 above the producer and carbonizing retort;

' Fig. 3 is a sectional, diagrammatic, elevation of a modification of the apparatus of Fig.1; r

Fig. 4 is a sectional plan view of the apparatus shown in Fig. 3, taken on the line 4-4 ofFig.3; j,

r Fig. 5 is a sectional, diagrammatic, elevation of another modification of the apparatus.

carbonized by contact with hot gas from a producer, serving at the same time to cool the gas and entrap and retain any pitch or solids which may be present in the hot gas. When the carbonization of the coal is sufliciently complete, it may be supplied to the gas producer and the gas produced in this producer may then be used to carbonize coal to be used in the producer. In carbonizing the coal, the hot producer gases are passed through the coal in a downward direction in such a manner that each layer of coal is first subjected to a low temperature carbonization by gases partly cooled in passing through the upper layers of the coal and are heated to progressively higher temperatures as the mass of coal heats up and as the final high temperature carbonizing zone passes downwardly through successively lower layers. The vaporized products of carbonization which may condense in the lower, cooler, portions of the coal tend to flow away from the carbonizing zones, thereby avoiding their destruction or decomposition through contact with the hot carbonized product, the carbonization is carried out preferably in retorts of limited cross sectional area,'a number of such retorts being arranged in parallel in the path of'the producer gases and the passage of the gases therethrough being controlled to provide uniform treatment for the coal in each retort. I

When the carbonization of the coal is completed, the resulting coke is at avery high temperature, that in the upper layers being near the temperature of the hot producer gas. To utilize this heat and to chill the coke steam is blown upwardly through the coke,

being superheated in the lower portion of the retort and, as it comes in contact with the upper, hotter portion of the body of coke, reacts therewith to form hydrogen and carbon difuel gases produced, in the producer.

oxide or carbon monoxide. These gases are then passed through the producer and serve to increase the total of gas production, the gases leaving the producer being, in this stage of the operations, passed through. a second or alternate set of retorts. As the producer gases generally contain more sensible heat than is required for the coal carbonizing operations and are at a much higher temperature than is required for carbonizing the coal, a portion of this heat is intercepted in ducer and the carbonizing coal in the retorts and is returned to the producer in such a manner as to be applied to the endothermic reactions and to increasing the quantity of l/Vhen there is an excess of hot producer gases over that required in carbonizing the coal, the

heat in a portion of the gases may be used en-- tirely for increasing the productionof gas 1n the producer by preheating the air supplled to the producer for combustion. By

coal in the retorts.

varying the'quantity of air thus used, the quantity of heat supplied to the carbonizing coal may be controlled in accordance with the requirements of coals of difierent characteristics.

Referring,,more particularly, to Figs. 1 and 2 of the accompanying drawings, a charge of coal or coke or other carbonaceous fuel such as oil shale or coal previously carbonized in the process, is supplied from a hopper. 10 through a conveyor 12 and chute 14: to a gas producer 16. The charge is received in a vertical shaft 18, extending upwardly from above a combustion zone 20 of the producer, and descends gradually to the combustion zone as the charge is consumed. The charge .is heated and any coal or other bituminous material therein is carbonized in its downward passage through the shaft 18 by hot gases passing upwardly therethrough from the combustion zone of the producer and reaches the combustion zone at temperature suitable for combustion.

In the combustion zone 20 the heated and carbonized charge, hereinafter referred to as coke, is burned to carbon monoxide by air supplied from a bustle pipe 22 through branch pipes 2% in theusual manner. The hearth of the producer is provided with a water jacket 25 having a water inlet 27 and a steam outlet 29. Some steam may be admitted through pipes 22, 24 and 29 to react with the hot coke to utilize some of the excess heat of the combustionfor the production of additional quantities of gas. Theslag resulting from the combustion is received in a receptacle 26 at the base of the producer and removed through a draw-off opening 28, a slagging type of. producer being illustrated in the drawings by way of example. It will be understood that when a slagg'ing type producer is used the chargeadmitted into chamber 18 may include a small proportion of a fluxing agent such as lime. It will also be understood that non-slagging producers may be used in place of the slagging producers illustrated. v 1

A large portion of thehot producer gas formed in the combustion zone 20 is withdrawn, in alternate periods, (Figs. 1 and 2) either through a vertical passage 30 at the right of the shaft 18, and a horizontal pas-, sage 32 tocoking reiortsfif, or through avertical passage 36 at the opposite side of the shaft 18 and a horizontal passage 38 to an alternate set of coking retortse'lQ. The retorts 34 and L0 during their respective periods for the passage of the hot gas are vkept filled with'coal or other fuel to be carbonized for usein the. producer 16, the hot gases being preferably passed downwardly through. the

1 As the hot producer gases come into contact with the bodies of coal, in retorts 34: for example, the gases are cooled by glvlngup their sensible heat to the coal. Any pitch which may be contained in the hot gases is thereby condensed, and as the mass of coal particles form an effective filtering medium, the pitch is caught on the coal and retained and later carbonized with the coal.

As the hot gases give up their heat the upper portions of the coal in the retorts 3% are rapidly brought to a carbonizing temperature and a quantity of hydrocarbon gases and coal distillation products are formed and carried through the retorts with the rapidly fiowing producer gases. As the upper portions of the coal become completely carbonized, the lower portions of the coal are gradually heated and distilled, and the temperature required for complete carbonization is carried to the lower part of the retorts until the coal is carbonized to the desired extent. The coal tar, ammonia and other products of distillation are immediately removed from the distilling zone as soon as they are formed and carried through progressively cooler zones thereby avoiding any tendency for their subsequent decomposition and ob taining the products at their lowest temperature of formation. 'Should any of these products be condensed by contact with unheated portions of the coal, there is no possibility of their falling back into the carbonizing zone as they will tend to gravitate or.

be carried with the flowing gases to progressively cooler zones.

If the dimensions of the carbonizing retorts 34 and 40 were increased to correspond with the increase in the size of the producer for large capacity producers, opportunity would be presented throughout the cross section of the retorts for an uneven carbonizing action due to the formation of chimneys through unevenness in the character or size of the coal or in its packing in the retort. The retorts are accordingly kept within limits of cross sectional dimensions such that chimneys do not tend to form or, if formed, are of such dimensions that heat sufficient for carbonization may be transmitted sidewise through the coal in the retort with sufiicient facility to insure carbonization throughout all portions of the retorts. When producers of larger capacity are employed, therefore, the number of the retorts, rather than their size, is increased. 7 r

In the embodiment of the invention shown in Figs. 1 and 2 of the drawings, four retorts are indicated on each side of the producer and each retort is provided with an individual gas offtake pipe 4.2 and a control valve 44 for controlling the quantity of gas passing from each retort to a collecting main 46 and thus regulating the action of the retorts. Each retort is also provided with an individual charging door 48 in its top wall through which coal may be supplied from a traveling hopper 50. Ordinarily the tar pro:

This heat is recovered whenthe producer gases are sent through the alternate retorts 40 by passing steam upwardly throughthe retorts and through the combustion zone of the producer. -This steamis supplied through a pipe 54 and control valve 56 to a distributing ring 58 at the lower part of the retorts; and, in passing upwardly through the retort, is superheated to a temperature at which it reacts with the hot cokein the upper part of the retort to form blue gas; This may be continued at a much lower temperature than would be desirable in a water gas apparatus since the objectionably large quantities of carbon dioxide formed at the lower temperatures are decomposed by heat from the combustion zone of the producer and transformed into carbon monoxide as the gases later pass through the producer. When the coke has been sufficiently cooled it is withdrawn through doors 60 in the bottoms of the retorts and quenched. It is then ready for use in the producer or for sale or other purposes. To keep the coke from contact with the steam distributing ring 58 it is preferably supported on a raised, perforated, supporting plate 61 mounted on the door 60.

The heat required to carbonize the coal is, in general, much less than the sensible heat carried by the gases obtained in the primary combustion of the coke produced. This excess of heat produced in the producer is decreased somewhat by the reduction of the quantity of coke through its combustion in the steaming of the retorts. To further decrease the excess of heat, checker brick 62 and 64 are provided in the passageways 30 and 36 through Which heat may be absorbed and returned to the producer. When coal is being carbonized in the retorts 34, for example, the hot producer gases first come into contact with the checkerwork 62, reducing the'temperature of the gases coming into contact with the coal in the upper part of the retorts, thus utilizing lower temperatures for the earbonization while the checkerwork is is reversed during the steaming of the retorts 34 and the carbonization in retorts 40, the heat absorbed in the checkerwork 62 is absorbed by the gases passing to the producer and serves to heat these gases. That portion of the heat produced in the producer which would ordinarily be used in heating these gases to the checkerbrick temperature is accordingly available for the endothermic reactions such as the dissociation of steam in the producer, thus increasing the quantity of gas produced through sensible heat abstracted from the hot producer gases. Similarly, the checkerwork 64 serves to abstract heat when coal is being carbonized in the retorts 40 and return it to the producer when the relation of the retorts is reversed. Through this arrangement, a portion of the heat of the producer gases lying between the temperature of the producer and the temperature of carbonization of the coal is abstracted from the gases in the checkerwork and in the previously carbonized coal and returned to the producer to be utilized in increasing the calorific value of the gas and the efficiency of conversion of the coal into gas.

In some cases the excess of heat in the producer gases may not be completely utilized in the manipulations outlined above, the excess depending to some extent on the type of coal used. In this case, a portion of the producer gases is withdrawn upwardly through the charge in the shaft 18, preheating this charge and carbonizing any coal therein preparatory to its passage to the producer, and is then passed through a pipe or conduit 66 to a heat interchanger 68 indicated diagrammatically in the drawings. The hot gases pass through passages 69 in the interchanger and give up their heat through a diaphragm 70, to air in passages 7 2 in the interchanger. From the passages 72 the air is supplied to the bustle pipe 22 and the combustion zone 20 of the producer. Since the gases are somewhat cooled in the shaft 18 and are small in quantity in comparison with the air to be heated, the walls and diaphragm of the heat interchanger are at a sufficiently low temperature to permit the use of heat resisting metal in its construction. The preheating of air in this manner diminishes the quantity of heat used in the combustion zone of the producer in heating the air to the reaction temperature and makes a larger quantity of heat available for the transformation of steam and carbon to hydrogen and carbon monoxide. The use of the heat interchanger may, however, be omitted and the gases pass ing upwardly through the shaft 18 may be passed to the passages 32 or 38 through passages 74 and 76 controlled by dampers as shown.

The retorts 40 are provided with gas outlets 80, control valves 82 and header 84 similar to those of retorts 34, and with a steam supply pipe 86 and distributing ring 88. 7 Charging doors 90, coal hopper 92 and tarsprays 9 4 are also provided. The area of and the removal of the carbonized coal. When necessary, the retorts may be jacketed to maintain the walls hot and enable the coal adjacent the walls to be completely carbonized.

The coal used in the process need notbe limited to the special grades required for the production of coke but any suitable coal or other suitable fuel may be used. When the 7 coal tends to become so pasty during carbonization as to materially impede the passage of the producer gases, the coal may be mixed prior to or during the charging of the retorts with sufiicient coke to provide the required porosity. A layer of coke 96, as indicated in the retort 40 in Fig. 1, is preferably placed in the bottom of the retort to protect the doors and steam inlets from burning out or clogging with tar. V

The preferred operation of the apparatus of Figs. 1 and 2 is briefly as follows Coke is supplied continuously through the shaft 18 to the combustion zone 20 of the producer and is burned to producer gas by means of air or air and steam supplied through pipes 22 and 24. The hot producer gases are withdrawn through the passages 30 and 32 and the checkerwork 62 therein and passed downwardly through coal in the carbonizing retorts 34. The producer gases and products of the distillation of the coal are withdrawn through the outlet pipes 42. When the coal in the retorts 34 is sufficiently carbonized, steam is-supplied to the lower part of the retorts through a pipe 54 and dis tributing ring 58 and passing upwardly through the retorts is superheated and transformed into carbon oxides and hydrogen. From the retorts the gases pass through the passages 32 and 30 and the hot checkerwork 60 and through the upper portion of the combustion zone 20 of the producer in which the completion of the transformation of the gases to hydrogen and carbon monoxide is accom plished. From the combustion zone the hot gases pass through passages 36 and 38 and checkerwork 62 to the retorts 40 to carbonize charges of coal in these retorts. \Vhen the coal in retorts 40 is carbonized and the coke in retorts 34 is cooled as much as practicable, the coke in retorts 34 is replaced with fresh charges of coal and the passage of gases is reversed. A portion of the gases produced in the combustion zone 20 are drawn upwardly through the shaft 18 heating the coke and carbonizing any coal therein and passes to the heat int'erchanger 66 to preheat air supplied to the pipes 22 and 24. The heat of the partial combustion of the fuel is accordingly efliciently used in the gas producing apparatus for the production of gas and carbonization of coal and'the gases are delivered in a sufliciently cool condition for efficient distribution without excessive waste of heat. It is to be understood that the cooled gases may be passed through any suitable tar extractors and scrubbing and purifying apparatus after leaving the retorts. The gases withdrawn through the pipes 4:6 and 84 may be blended with the gas withdrawn through the pipe 66 when desired.

In the modification of the apparatus illus trated in Figs. 3 and 4 provision ismade for applying heat externally to the retort by'allowing a portion of the gas leaving the producer to pass outside of the retort walls in annular passages 98. The sensible heat of the gas thus conducted through passages 98 and eiftakes may alone be used or secondary air may be added through an inlet 102 in amounts suificient to burn this portion of the producer gas and thereby utilize the potential heat thereof for furnishing additional heat for carbonizing coal charges in the retort.

The apparatus of Figs. 3 and 4 embodies another modification in the series of steam nozzles 104: shown at different levels throughout the height of the retort. By means of these nozzles steam may be introduced in the reto-rts, either continuously or intermittentlv, thus allowing for use of the coke formed in the retort in a regenerative capacity as well as for its partial consumption byreaction with the steam. The introduction of steam into the retort serves to retard the rate of carbonization of the coal and allows for the conversion of a greater quantity of the coke product of carbonization into water gas in the retort itself, rather than in the producer. The preferred plan of operation contemplated when steam nozzles 104 are employed is as follows: After a body of coke is formed in the upperpart of the retort the direction of the producer gas flow through the apparatus is reversed and steam is introduced into the retort slightly above the zone of carbon-ization. After the coke has been cooled to the desired extent, the producer gas flow is again reversed and the retort-s on the opposite side of the producers are steamed in a similar manner. This alternate operation of the retorts is carried on until carb'onization is completed, the plan of operation being otherwise much the same as that previously described for the apparatus of Figs. 1 and 2. By this method of operation the same body of coke can be heated and steamed alternately sever al times during'the process of carbonizng the fullretort charge.

In Fig. 5 a further modification of the apparatus is illustrated, such modification being designed to permit gas formed in steaming a retort to pass downwardly through an adjacent carbonizing retort without passing through the producer fuel bed. Thus at the same time that producer gas is being passed through or around one of the retorts illustrated in Fig. 5, the valves in the ofitake connections may be so arranged as to permit upsteaming of. the other retort,the gas result ing from such up-steaming being also passed downwardly through or around the retort through or around which producer gas, or a portion of the producer gas, is being passed. This apparatus may also be operated intermittently in such a way as to remove all the producer gas through the shaft 18 at the top of the producer, and all of the gas generated in the retorts separately through one of the retort of'ftakes. Thus this arrangement per mit-s the production of a producer gas which is free of hydrogen and may be used without admixture with the blue gas if so desired; as for example in highcompression internal combustion engines.

Another modification of the apparatus is shown in Figs. 6' and 7 This modification enables a further segregation of the various types of gases; In this modification the partition walls 108 divide the upper part ofthe producer into four compartments 110, each compartment being separated from the others at its top and being provided with chutes 14 whereby the producer may be charged with coal or coke fuel. The central'partition- 108 extends downwardly into the producer farther than the outside partitions.

The preferred plan of operation of this modification of the apparatus is much the same as that of the other modifications previous ly described except that the gases formed by retort steamingmay be conducted only partially across the producer fuel bed and may be drawn off with a minimum of producer gas intermingled with them, through the offt-ake connection 66 leading from the side of the producer nearest'the retort un dergoing steaming while at the same time a dry producer gas may be drawn off, unmixed with either water gas or coal gas,through the oiftake connection 66 on the opposite side of the. central partition 1081 This niodi-fication of apparatus is therefore adapted for operation in such a way as to yield at least three comparatively well defined separate types of gaseous products, which may be kept separate if their value is found to be greater thus than when combinedinto a single mixture. In the modification of Figsi6. and 7 the bodies of coal or coke in the compartments 110 in the upper portion of'the producer act in a regenerative capacity in the place of the checker brick 64 of the apparatus of Figs. 1 and 2, and are gradually consumed by decomposition into blue gas. j

The object sought by the various modifications of the apparatus illustrated is flexibility in operation to produce flexibility in products. Thus the arrangement of the various apparatus modifications shown is" such that almost any typeof gas desired may be obtained by means of the various combinations andblendingsof coal gas, water gas and producer gas which are permittedby adjustments in the operation of the apparatus illustrated. Any particular product of the carbonization or gasification of coal may be made as a major product, by-product, or may be eliminated, as desired.

Having described the invention, what I 7 claim and desire to secure by Letters Patent is:

1. An apparatus for producing gas and coke which comprises, a gas producer, a plurality'of carbonizing retorts each having a fuel charging member at one end and a coke discharge member at its other end, said retorts being arranged at different sides of said producer, separate conduits communicably connecting the producer and the charging ends of the retorts respectively, separate valved gas withdrawal outlets from the discharge end of each retort, and steam conveying means communicably connected by valved passages to the discharge end of each retort.

2. In apparatus for producing gas and coke, a gas generator having an air inlet and a gas offtake, a vertical carbonizing retort having a coke discharging member at its lower end, a gas conduit communicably connecting the generator and the retort at its upper end, a gas withdrawal outlet from the lower end of the retort, and a steam supply means communicably connected with the lower end of the retort.

3. In coal carbonizing and gas generating apparatus, a gas producer, a vertical carbonizing retorthaving a fuel charging inlet at its top and a charge supporting and dis-. charging members at its lower end, a gas olftake port in the discharge end of said retort, a conduit adapted to conduct gas from said producer to the top of said retort from whence'it may pass downwardly therethrough to said ofi'take, a fuel feeding shaft communicating at its discharge end with said producer, and gas offtake means at the inlet end of said shaft through which gas may be discharged after pass ng from said producer through said shaft.

4. Fuel carbonizing and gas generating apparatus comprising, a gas producer having an air inlet and a valved gas'offtake, a vertical carbonizing retort having a coke discharging member at its lower end, a gas conduit communicably connecting the producer and the retort at its upper end, and a valved gas withdrawal outlet from the lower end of the retort. A p

5. In coal carbonizing and gas generating apparatus, a gas producer, a vertical carbonizing retort having a fuel charging inlet at its top and a charge supporting and discharging member at its lower end, a gas ofitake port in the discharge end of said retort, a gas conduit communicably connecting the producer and the retort at its upper end, a fuel feeding shaft communicating at its discharge end with said producer, a gas ofi'take port at the inlet end of said fuel feeding shaft through which gas may be discharged after passing from said producer through said shaft, a heat interchanger, and separate conduits communicably connecting the heat interchanger with the gas offtake port of said feeding shaft and with the air inlet of said producer.

6. Apparatus for producing gas and carbonizing fuel comprising, a gas producer, a carbonizing retort, a gas conveying conduit communicably connecting the producer and retort, a steam conveying means communicably connected with the retort, an annular heating fiue surrounding the retort, and communicating with the conduit, and separate valved gas outlets in the retort and in the annular heating fiue, respectfully.

7. Apparatus for producing gas and carbonizing fuel comprising, a gas producer communicably connected by an open conduit with the top of a vertical carbonizing retort, and also with an annular heating flue surrounding said retort, a fuel charging inlet at the top of said retort, mechanism at the bottom of said retort for discharging car bonized fuel, and separate valved gas outlets in the foot of said retort and in the base of I said heating flue respectively.

8. Apparatus for producing gas comprise ing a vertical gas producer, a fuel preheating chamber superimposed above and in direct communication with said gas producer, an open conduit communicably connecting the gas producer with the top ofa vertical carbonizing retort, a valved passage adapted to communicably connect said conduit with the top of said preheating chamber, a gas oiftake at the top of said preheating cham ber, a valved gas ofitake at the foot of said retort, and means for introducing steam into said retort.

9. In coal carbonizing and gas generating apparatus, a gas producer, an elongated carbonizing retort having a coal charging inlet at one end and a coke discharging member at its other end, a gas ofi'take port in the coke discharge end of said retort, a conduit communicably connecting the producer and carbonizing retort at the charging end of the retort, steam conveying means communicably connected with the discharge end ofsaid retort, and means distinct from said conduit through which gas may be withdrawn from the producer.

In testimony whereof I affix my signature.

WILBUR G. LAIRD. 

